Can I Keep Driving With a Check Engine Light?

Can you keep driving when the check engine light comes on? The short answer? Probably. But you probably knew there wasn’t going to be a black and white answer when you typed the question into Google. Let’s chat. I’ll try to keep it short so you can get on with your day.

You may be in the middle of a trip, or on your way to an important appointment, and of course! The car has to go and throw a fit. Generally, if the car still seems to be running OK, and the check engine light isn’t flashing, and the temperature gauge and oil light look normal, you’re probably fine to keep driving and get where you’re going.

The check engine light can come on for tens of thousands of reasons. There may be only hundreds of trouble codes (a trouble code sets whenever the check engine light comes on), but there are hundreds of possible causes for each trouble code. Why’d your light come on? Sorry, I don’t know, at least not over the phone without looking at the car.

Sometimes the check engine light comes on for a reason for the smallest of problems. If you leave your gas cap loose, the check engine light will eventually come on. Is that going to cause the car to break down? Absolutely not. It will increase emissions though, and a lot of the time, that’s why the check engine light is on — there’s a problem that will cause the emissions to increase but won’t interfere with safe driving of the car.

Sometimes a check engine light isn’t a big deal, but, you guessed it, sometimes it is. For instance, if the engine is low on oil, and you brake hard, all of the oil sloshes to the front of the oil pan and whammo!, the oil pickup runs dry and the oil pressure drops. The variable valve timing system relies on oil pressure to work and it sets a code. Running out of oil could do so much damage to the car that it won’t even be worth fixing. In this case, you’d better treat the check engine light like an emergency.

So how do you tell the difference? A minor emissions problem or impending doom. It’s only one light and it only has two states: on, and off. Here what I tell people several times per day :

1. If the check engine light is flashing, towing the car to a repair shop is the safest bet. A flashing check engine light indicates a misfire, which can cause very expensive damage to the catalytic converter. Some cars will cut the injector to the misfiring cylinder to protect the catalyst; others won’t. If you do decide to risk a drive, drive very gently.

2. Check the temperature gauge. If the car is overheating, don’t drive it. Tow it. Overheating can quickly ruin an engine. No temperature gauge? Check for red thermometer icon with squiggly lines meant to represent water.

3. Check the oil level. A gas station is a great place to do this because the ground is likely pretty level, which is important for getting an accurate engine oil reading. Also, they’ll likely have oil for sale if you need it. By the way, another commonly asked question is “what kind of oil should I use”? You should be able to find the correct oil weight (0W20, 5W30, etc.) on the oil cap or in the owner’s manual. Or you can always type, “What kind of oil does a 2015 Civic take into Google. Can’t find the answer? Don’t worry too much about it. Any oil is better than no oil. If it’s low, add whatever motor oil you can find.

4. Is the car driving abnormally? If so, a tow is a better way to go.

5. If you need to keep using the car, and we’re all booked up and can’t get you in right away, swing by and we’ll check the code. Once we know what code you have, we’ll be able to let you know whether it’s safe to keep driving. Remember, you can always rent a car from Rent-a-Relic for $25/day, which is a lot cheaper than doing unnecessary damage to your car.

6. Don’t just ignore it and keep on driving forever. Even if you find you have an emissions related code that’s not going to cause you to break down, you only have one check engine light. If a more serious problem crops up, you have no way of knowing it’s something different; there’s only one check engine light.